britishwildlifefandomcom-20200215-history
Goosander
]The Goosander (Mergus merganser) is a large duck, of rivers and lakes of forested areas of Europe, northern and central Asia, and North America. It eats fish and nests in holes in trees. Description It is 58-72 cm (29.7 in) long with a 78-97 cm (39.8 in) wingspan, and a weight of 0.9–2.1 kg; males average slightly larger than females but with some overlap. It has a crest of longer head feathers, but these usually lie smoothly rounded behind the head, not normally forming an erect crest. Adult males in breeding plumage are easily distinguished, the body white with a variable salmon-pink tinge, the head black with an iridescent green gloss, the rump and tail grey, and the wings largely white on the inner half, black on the outer half. Females, and males in 'eclipse' (non-breeding plumage, July to October) are largely grey, with a reddish-brown head, white chin, and white secondary feathers on the wing. Juveniles (both sexes) are similar to adult females but also show a short black-edged white stripe between the eye and bill. The bill and legs are red to brownish-red, brightest on adult males, dullest on juveniles. Behaviour These fish-feeding ducks have serrated edges to their bills to help them grip their prey; they are therefore often known as "sawbills". In addition to fish, they take a wide range of other aquatic prey, such as molluscs, crustaceans, worms, insect larvae, and amphibians; more rarely, small mammals and birds may be taken. As in other birds with the character, the salmon-pink tinge shown variably by males is probably diet-related, obtained from the carotenoid pigments present in some crustaceans and fish. When not diving for food, they are usually seen swimming on the water surface, or resting on rocks in midstream or hidden among riverbank vegetation, or (in winter) on the edge of floating ice. The species is a partial migrant, with birds moving away from areas where rivers and major lakes freeze in the winter, but resident where waters remain open. Breeding Nesting is normally in a tree cavity, thus it requires matures forest as its breeding habitat; they also readily use large nest boxes where provided, requiring an entrance hole 15 cm diameter. The female lays 6–17 (most often 8–12) white to yellowish eggs, and raises one brood in a season. The ducklings are taken by their mother to rivers or lakes immediately after hatching, where they feed on freshwater invertebrates and small fish fry, fledging when 60–70 days old. The young are sexually mature at two years old. Status and conservation Overall, the species is not threatened, though illegal persecution by game fishing interests is a problem in some areas. Within western Europe, there has been a marked southward spread from Scandinavia in the breeding range since about 1850, colonising Scotland in 1871, England in 1941, and also a strong increase in the population in the Alps. The Goosander is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies. Gallery Channel Islands absent.jpg|Distribution of Goosanders on the Channel Islands Category:Birds Category:Waterfowl Category:Anseriformes Category:Vertebrates Category:Chordata Category:Anatidae